A self-contained unit designed for placement in the holder of a respirator or air line mask. It may consist of a filtering element of fibrous material such as felt, paper, or the like secured between two end plates; or it may be a cylindrical container of light weight construction having flat or slightly rounded ends which may be either perforated or of wire mesh, filled with charcoal or chemicals which absorb contaminants from the air passing through it. See also FILTER, RESPIRATOR, AIR FILTERING.